1. Field of the Invention
The invention relates to a central locking equipment for vehicle doors, provided with drive units for locking the individual doors. Each drive unit contains a reversible electromotor with reduction-gear which drives a locking linkage by means of a driven lever. The locking linkage can also be operated by hand.
2. The Prior Art
The German printed patent application No. P 19 55 239 discloses a servo-activated locking equipment for vehicle doors. That equipment contains several drive units with reversible electromotors. Each motor operates through a reduction gear and linkage on the locking lever of the lock. In addition, a linkage rod connects the lever with a locking button which is activated by hand. In the linkage between the drive unit and the lock, a control switching device is mounted in the front doors which reacts to tension or pressure to switch the motor into the left or right running mode, respectively. If, for example, the driver's door is locked from the outside, the closing motion exerts such a pressure on the control switching device that it makes contact and starts the motors of the drive units of the other doors. Therefore, all doors are locked simultaneously, and they are also unlocked when unlatched. Nevertheless, each door can be unlocked individually from the inside by lifting the respective locking button. Due to the mechanical coupling for the transmission and the motor of the corresponding drive, these elements are still on line during this procedure and are thus manually operated. Because the toothed segment and pinion of the transmission provide a large mechanical advantage, manual operation requires application of considerable force. A further disadvantage is presented by the complicated assembly and the inexact disengagement of the motor, which can cause failures.